Detection of Glucose Based on Gold & Silver Nanoparticles using Z-scan Technique
Diabetes is a common chronic disease, characterized by defects in insulin action, secretion or both causing hyperglycemia. Diabetes can have serious long-term complications as it important to control blood glucose levels. Chemical and optical methods are used mainly in measuring glucose levels. Chemical methods require drawing blood several times a day which is uncomfortable for the patient. Optical sensor measurements are affected by physical and chemical parameters and environmental changes.
In this study, we propose a method for detecting and quantifying blood glucose levels based on the nonlinear optical properties measurements using the z-scan technique. Gold, silver and gold/silver (core/shell) nanoparticles were synthesized using a wet chemistry where trisodium citrate was used as a reducing agent. A green synthesis method used curcumin and glucose as reducing agents. These nanoparticles are characterized by their plasmon absorbance band, and their shapes and sizes are confirmed by TEM. Glucose conjugated nanoparticles are either synthesized or mixed with glucose. The compositions of these conjugates were confirmed by TEM. Mie theory was used to determine the size of the nanoparticles. Nanoparticles conjugated with glucose were subjected to nonlinearities measurements using the z-scan technique. The z-scan experiments were preformed using 488 nm and 514 nm CW argon-ion laser with adjusting power of 15 – 30 mW to measure the nonlinear refractive index ( ). Z-scan measurements indicated that studied samples exhibited nonlinear optical properties. The experimental results show that the nonlinear refractive index was dependent on the concentration of glucose conjugated with metal particles. Thus, the nonlinear refractive index value of the given glucose sample may be used as a quantifying indicator.